Sample Ktor websocket project, both client and server are 2.3.11. Client sends binary frames with fi...

# ktor

[Sergey Aldoukhov]

Sample Ktor websocket project, both client and server are 2.3.11. Client sends binary frames with fin=false, server receives fin=true. I have traced this to using ktor-client-okhttp, cio works as expected. is this a known bug?

[Aleksei Tirman [JB]]

Do you mean the Chat sample? What must be changed there to reproduce the bug?

[Sergey Aldoukhov]

No I meant my own sample.
Server:

routing {
        webSocket("/ws") { // websocketSession
            for (frame in incoming) {
                if (frame is Frame.Binary) {
                    val bytes = frame.readBytes()
                    println("Received ${bytes.size} fin ${frame.fin}")
                }
            }
        }
    }

Client:

runBlocking {
        client.webSocket(HttpMethod.Get,
            "localhost",
            8080,
            "ws",
            request = {
                headers {}
                url.protocol = <http://URLProtocol.WS|URLProtocol.WS>
            }
        ) {
           send(Frame.Binary(false, ByteArray(10))
...

[Sergey Aldoukhov]

Here is the client build:

product: jvm/app

dependencies:
  - io.ktor:ktor-client-core:2.3.11
  - io.ktor:ktor-client-okhttp:2.3.11
  - io.ktor:ktor-client-websockets:2.3.11

settings:
  kotlin:
    languageVersion: 1.9

If ktor-client changes to ktor-client-cio the bug disappears

[Sergey Aldoukhov]

There is also another bug on top of that, also happen with okhttp client only. If I send a lot of data without acknowledgements, the packets stop arriving at the destination as soon as the amount sent is larger than 16mb.

[Aleksei Tirman [JB]]

I've reproduced the problem. I guess it's a limitation of the OkHttp client because their Websocket.send method doesn't accept the Fin parameter. Also, the documentation says the following about your second problem:

Messages that would overflow the outgoing message buffer (16 MiB) will be rejected and trigger a graceful shutdown of this web socket.

[Aleksei Tirman [JB]]

Nonetheless, I can file the issues if you like.

[Sergey Aldoukhov]

Well, to me it doesn’t matter anymore, but I’d file an issue with OkHttp…